It was early found, that, if the excavation was made just deep enough so that the base plate could be set at the proper angle, the drums or projectiles were fired as accurately as when the projectors or mortars were set so that the muzzles were level with the surface. The time required to emplace a given number of mortars in this way was only about one-fifth of that required for digging them completely in. Coupled of course with these proposed improvements in methods, studies were being made and are still being made to produce lighter mortars, better powder charges, and better gas checks in order to develop the full force of the powder. Many improvements along this line can be made, all of which will result in greater mobility, more frequent attacks, and hence greater efficiency. =4-Inch Stokes’ Mortar.= The Stokes’ mortar is not different from that used by the Infantry, except that it is 4-inch, while the Infantry Stokes’ is 3-inch. The 4-inch was chosen by the British for gas, as it was the largest caliber that could be fired rapidly and yet be moderately mobile. Its range of only about 1,100 yards handicapped it considerably. The poor design of the bomb was partly responsible for this. The powder charges also were neither well chosen nor well designed. It is believed that great improvements can be made in the shape of the bomb and in the powder charge, which will result in much longer range and high efficiency, while in no way increasing the weight of the bomb or decreasing the rate of fire. These last two weapons were used during the World War, and will be very extensively used in the future for firing high explosive, phosphorus, thermit and similar materials that non-technical troops might handle. Since gas has proven without the shadow of a doubt, that it will produce more casualties for an equal amount of material transported to the front than any other substance yet devised, all troops using short range guns or mortars should be trained to fire gas whenever weather conditions are right. When weather conditions are not right, they should fire the other substances mentioned. The Livens’ projector with its 60 pound bomb, of which 30 pounds will be gas or high explosive, is a wonderful gun up to the limit of its range. The bomb, not being pointed, does not sink into the ground, and hence upon exploding exerts the full force of high explosive upon the surroundings, whether bombs, pill boxes, barbed wire or trenches, to say nothing of personnel.